HTML <bdi> Tag

The HTML <bdi> tag creates a 'Bi-Directional Isolation' element. It is used on a span of text that is to be isolated from its surroundings for the purposes of bidirectional text formatting.

The <bdi> tag can be useful when displaying right-to-left text (such as Arabic) inside left-to-right text (such as English) when the text-direction is unknown. The <bdi> element allows you to honor the correct directionality of text when this is unknown (such as in the case with user-generated content).

The basic tag is written like this <bdi></bdi>.

You can also use CSS to acheive the same visual effect (using inicode-bidi: isolate on a <span> or other text formatting element), but that method doesn't convey the semantic meaning. In order to convey the semantic meaning, use the <bdi> element.

Also note that browsers can ignore CSS, in which case, the desired text directionality would not be acheived, unless the HTML document uses the <bdi> tag.

The <bdi> tag was introduced in HTML 5.

Example

The following example shows the <bdi> element in action. You can modify the code (on the left) and click "Refresh" to see your changes take effect (on the right).

Source Code

Result

Attributes

The <bdi> tag accepts the following attributes. Try adding some to the above example to see how it affects the display/behavior of the element.

Attributes Specific to the <bdi> Element

None. However, note that the global dir attribute defaults to auto on this element (it never inherits from the parent element like with other elements).

Global Attributes

The <bdi> tag accepts the following global attributes. These attributes are standard across all HTML 5 tags.

Attribute

Description

accesskey

Specifies a shortcut key that can be used to access this <bdi> element.

Possible values.

[Any string of characters. This string of characters specifies the key/s the user needs to use in order to access the element.]

class

This is a document wide identifier. It is used to refer to a class that is specified in the style sheet. The value should match the name of the class you wish to use.

contenteditable

This attribute specifies whether the user can edit the content or not.

Possible values:

true

false

contextmenu

The contextmenu attribute sets a context menu for an element. The value must be the ID of a menu element in the DOM.

dir

Specifies the direction of the text.

Possible values:

Value

Description

ltr

Specifies that the text should read left to right.

rtl

The text should read right to left.

auto

The text direction should be determined programatically using the contents of the element.

draggable

Specifies whether the user is allowed to drag this <bdi> element or not.

Possible values:

true

false

auto

Value

Description

true

This value specifies that the element is draggable.

false

A false value specifies that the element is not draggable.

auto

Uses the default behavior of the user agent/browser. This is the default value.

dropzone

The dropzone attribute specifies what should happen when the user "drops" an element (i.e. after dragging it) onto this <bdi> element.

Must be an unordered set of unique space-separated tokens that are ASCII case-insensitive.

Possible values:

Value

Description

copy

Results in a copy of the dragged data. Default value.

move

Results in the data being moved to the new location.

link

Results in a link to the original data.

Any keyword with eight characters or more, beginning with the an ASCII case-insensitive match for the string "string:"

Specifies that items with the drag data item kind Plain Unicode string and the drag data item type string set to a value that matches the remainder of the keyword are accepted.

Any keyword with six characters or more, beginning with an ASCII case-insensitive match for the string "file:"

Allows you to specify which file types can be processed (i.e. copied, moved or linked) in this dropzone. Example: dropzone="copy file:image/png file:image/gif file:image/jpeg"

Note that this attribute must not have more than one of the three feedback values (copy, move, and link) specified. If none are specified, the copy value is implied.

hidden

Indicates that this particular <bdi> element is not yet, or is no longer, relevant. The browser/user agent does not display elements that have the hidden attribute present.

This is a boolean attribute. If the attribute is present, its value must either be the empty string or a value that is an ASCII case-insensitive match for the attribute's canonical name, with no leading or trailing whitespace (i.e. either hidden or hidden="hidden").

Possible values:

[Empty string]

hidden

id

The id attribute is a document wide identifier, which is used in conjunction with CSS and JavaScript. The value must match the name of the id you wish to use.

itemid

The itemid provides a global identifier for an "item". This attribute is optional, however if it is provided, it must have a value that is a valid URL potentially surrounded by spaces.

The itemid attribute can only be present in elements that include both the itemscope and the itemtype attributes, as long as the itemtype attribute specifies a vocabulary that supports global identifiers for items, as defined by that vocabulary's specification.

itemprop

This attribute provides one or more properties to one or more "items".

Although this attribute is optional, if used it must have a value that is an unordered set of unique space-separated tokens that are case-sensitive, representing the names of the name-value pairs that it adds. The attribute's value must have at least one token. Each token must be one of the following:

A valid URL that is an absolute URL, or

If the item is a typed item: a "defined property name" allowed in this situation according to the specification that defines the relevant types for the item, or

If the item is not a typed item: a string that contains no U+002E FULL STOP characters (.) and no U+003A COLON characters (:).

Also, Specifications that introduce defined property names that are not absolute URLs must ensure all such property names contain no U+002E FULL STOP characters (.), no U+003A COLON characters (:), and no space characters.

itemref

This attribute is used in conjunction with the itemscope attribute, the itemref attribute provides a list of additional elements to crawl to find the name-value pairs of the "item". Although the itemref attribute is optional, if specified, it must have a value that is an unordered set of unique space-separated tokens that are case-sensitive, consisting of IDs of elements in the same home subtree. Also, the itemref can only be used on elements that also have the itemscope attribute present.

itemscope

HTML5 elements that have the itemscope attribute create a name-value pair called an "item". Elements with an itemscope attribute may also have an itemtype attribute specified, to give the item types of the item.

This is a boolean attribute. If the attribute is present, its value must either be the empty string or a value that is an ASCII case-insensitive match for the attribute's canonical name, with no leading or trailing whitespace (i.e. either itemscope or itemscope="itemscope").

Possible values:

[Empty string]

itemscope

itemtype

This attribute provides an item type for elements containing the itemscope attribute. The attribute is optional but if it is specified, it must have a value that is an unordered set of unique space-separated tokens that are case-sensitive, each of which is a valid URL that is an absolute URL, and all of which are defined to use the same vocabulary. The attribute's value must have at least one token.

The itemtype attribute must only be present in elements that include the itemscope attribute.

lang

Sets the language code to be used.

Possible values:

[Must be a valid RFC 3066 language code, or an empty string.]

spellcheck

Specifies whether the element should have its spelling checked.

Value

Description

[Empty string]

The element should have its spelling checked.

true

The element should have its spelling checked.

false

The element should not have its spelling checked.

If this attribute is missing, the element will use the default behavior, possibly based on the parent's own spellcheck state.

style

Specifies inline styles for this <bdi> element. This allows you to define the styles within the page, and within this <bdi> tag, as opposed to referring to styles defined elsewhere (such as an external style sheet). Although this can be useful for over-riding external styles, it is usually preferrable to use external styles in conjunction with the class attribute and/or the id attribute.

tabindex

Helps determine the tabbing order for this <bdi> element (for when the user uses the "tab" key on their keyboard to "tab" through the elements on the page in order to select an element).

Possible values:

[Any valid integer. For example, 0, 1, 2, 3, ...etc]

title

Specifies a title to associate with this particular <bdi> element. Many browsers will display this when the cursor hovers over the element (similar to a "tool tip").

Possible values:

[Any text to be displayed as a "tool tip".]

translate

Determines whether the element's attribute values and the values of its Text node children are to be translated when the page is localized, or whether to leave them unchanged.

The translate attribute is an enumerated attribute and may contain the following possible values:

[Empty String]

yes

no

If the translate attribute is provided, but its value is missing or is invalid, the element will inherit its value from its parent element.

Event Handler Content Attributes

An event handler content attribute is an attribute for a specific event handler. The name of the content attribute is the same as the name of the event handler.

Event handlers are commonly used to extend the functionality of an HTML element. By using any of the event handler content attributes below, you can tell the browser to run a specific script and when to run it. For example, by using onclick="", you tell the browser to run a piece of JavaScript whenever someone clicks on the element. The JavaScript needs to be inserted between the double quotes. This is typically a small piece of JavaScript that simply calls a JavaScript function that has been defined elsewhere.

Here are the event handler content attributes that can be used with the <bdi> element.

Attribute

Description

onabort

Invoked when an event has been aborted. For example, the browser stops fetching media data before it is completely downloaded.

onblur

User has left the focus of the element.

oncancel

cancel event handler.

oncanplay

Invoked when the browser/user agent can start playing media, but hasn't yet, due to buffering. In other words, if playback were to begin now, it wouldn't play right to the end (due to the current playback rate) - it would need to pause during playback in order to load the rest of the media.

oncanplaythrough

The browser/user agent estimates that if playback were to begin now, the media resource could be rendered at the current playback rate all the way to its end without having to stop for further buffering.

onchange

User has changed the object, then attempts to leave that field (i.e. clicks elsewhere).

onclick

Invoked when the user clicked on the object.

onclose

close event handler.

oncontextmenu

Invoked when a context menu has been triggered.

oncuechange

cuechange event handler.

ondblclick

Invoked when the user clicked twice on the object.

ondrag

Invoked when an element is being dragged.

ondragend

Invoked when an element has stopped being dragged.

ondragenter

Invoked when an element has been dragged to a drop target.

ondragexit

dragexit event handler.

ondragleave

Invoked when an element leaves a valid drop target.

ondragover

Invoked when an element is being dragged over a valid drop target.

ondragstart

Invoked when a drag operation has started.

ondrop

Invoked when an element is being dropped.

ondurationchange

Invoked when the length of the media is changed (i.e. the duration attribute has just been updated).

onemptied

Invoked when a media resource element suddenly becomes empty (for example, due to a network error).

onended

Invoked when the media has reached the end.

onerror

Invoked when an error occurs while the element is being loaded. Also handler for script error notifications.

onfocus

Invoked when the focus is on the element.

oninput

input event handler.

oninvalid

invalid event handler.

onkeydown

Invoked when a key was pressed over an element.

onkeypress

Invoked when a key was pressed over an element then released.

onkeyup

Invoked when a key was released over an element.

onload

The element has loaded.

onloadeddata

Invoked when the browser/user agent can render the media data at the current playback position for the first time.

onloadedmetadata

Invoked when the browser/user agent has just determined the duration and dimensions of the media resource.

onloadstart

Invoked when the browser/user agent has started loading the media resource.

onmousedown

The cursor moved over the object and mouse/pointing device was pressed down.

onmousemove

The cursor moved while hovering over an object.

onmouseout

The cursor moved off the object

onmouseover

The cursor moved over the object (i.e. user hovers the mouse over the object).

onmouseup

The mouse/pointing device was released after being pressed down.

onmousewheel

Invoked when the mouse wheel is being rotated.

onpause

Invoked when the media resource has been paused.

onplay

Invoked when the media resource starts playback.

onplaying

Playback has begun.

onprogress

The browser/user agent is fetching media data the.

onratechange

Invoked when the playback rate has changed (i.e. either the defaultPlaybackRate or the playbackRate has just been updated).

onreset

reset event handler.

onresize

resize event handler.

onscroll

scroll event handler. Invoked when the element's scrollbar is being scrolled.

onseeked

Invoked when the seeking IDL attribute changed to false (i.e. the seeking attribute is no longer true)

onseeking

Invoked when the seeking IDL attribute changed to true and the seek operation is taking long enough that the user agent has time to fire the event.

onselect

Invoked when some or all of the contents of an object is selected. For example, the user selected some text within a text field.

onshow

show event handler.

onstalled

Invoked when the browser/user agent is trying to fetch media data but the data has stalled (i.e. the data has stopped coming).

onsubmit

User submitted a form.

onsuspend

The browser/user agent is (intentionally) not currently fetching media data, but has not yet downloaded the entire media resource (i.e. it has suspended the download).

ontimeupdate

Invoked when the media's current playback position changed.

onvolumechange

Invoked when either the volume attribute or the muted attribute has changed.

onwaiting

The next frame of the media is not yet available (but the browser/user agent expects it to become available).

More Information About the <bdi> Element

Content Categories

Flow content, Phrasing content, Palpable content.

Can be used

Where phrasing content is expected.

Content model

Phrasing content.

End Tag Required?

Yes. Any time you use the <bdi> element, it must have both a start tag and an end tag.